Sealing Structure of Container and Lid for Such Structure

ABSTRACT

A sealing member  13  is heat-sealed to the upper end surface of the mouth portion  12  of a container, and a lid  15  which is provided with a top panel  15   a  that covers the mouth portion  12  of the container, and which has an inner peripheral projection  15   e  that is positioned in the vicinity of a place inner than the inner periphery of the mouth portion  12  of the container on the inside surface of the top panel  15   a  is fitted to the mouth portion  12  to make it easy to peel (open and peel) the sealing member  13  while high sealing property is ensured, and to prevent the seal member  13  from peeling at the inner periphery of the mouth portion  15  of the container which peeling is caused by a rise in the internal pressure in the container.

TECHNICAL FIELD

The present invention relates to a sealing structure of a container which makes it easy to open and peel the seal member though it ensures high sealing property by sealing the mouth portion of a container with a seal member and by providing the container with a lid, and to a lid used for above container.

BACKGROUND ART

For instance, Patent Document 1 discloses retort plastic container in which the opening of the body of the container is sealed with an inner lid made of a plastic sheet by bonding the sheet with a bonding strength under which the sheet is more peelable from the container body, and an outer lid is covered on the inner lid and screw-fitted to the container body. According to the retort plastic container disclosed in Patent Document 1, it is reported that the inner lid with which the container is sealed is not peeled during retort sterilization treatment but can be peeled easily when the lid is opened.

Also, Patent Document 2 discloses a pouch spout produced by thermally welding a seal member on the top panel of an pouring cylinder and by screw-fitting a cap, provided with a contact ring on its inside surface that is in direct contact with the top panel of the pouring cylinder. The pouch spout disclosed in Patent Document 2 ensures that because the seal member is pressed by the contact ring and the sealing property of the seal member can be therefore improved, it is unnecessary to increase the adhesive strength of the seal member to a required level or more and the seal member can be easily opened and peeled when the content is poured from the pouch spout.

Also, Patent Document 3 discloses a package bag with a mouth in which the outer periphery of a seal material is fused with the outside surface of the opening end of the mouth portion and the seal material that seals the opening end of the mouth portion is pressed by a dome-like projection disposed on the backside of a cap. According to the package bag with a mouth portion which is disclosed in Patent Document 3, the dome-like projection does not break the seal material but is in close contact with the seal material, making it possible to prevent water from penetrating into the upper surface of the seal material that seals the mouth portion at the time of heat treatment.

Patent Document 1: Japanese Patent Application Laid-Open No. 6-219464

Patent Document 2: Japanese Patent Application Laid-Open No. No. 2002-104453

Patent Document 3: Japanese Patent Application Laid-Open No. 2004-224355

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

However, the container of Patent Document No. 1 has the problem that though the inner lid made of a plastic sheet is pressed against the upper surface of the opening of the container by a packing made of silicone rubber that is disposed on the inside surface of the outer lid, the inner lid is peeled from the upper surface of the opening on the inner peripheral side of the upper surface of the opening when the pressure in the container is raised when the container is sterilized at high temperatures or when a impact of falling is applied and the inner lid is raised towards the inside of the outer lid against the elastic force of the packing of the packing. When even a part of the inner peripheral side of the inner lid is peeled off, this is undesirable because the content in the container enters into that part and there is a fear of giving a feeling of discomfort to purchasers when the container is opened.

Particularly, in the case of containers, such as a spout pouch and squeeze bottle, which are made of flexible materials, the containers are largely deformed and the degree of a rise in internal pressure is increased when a impact of falling during the distribution process is applied or persons in charge strongly grasp them. Along with the increase in the internal pressure, the impact applied to the inner lid is increased when the internal pressure is raised. There is therefore a tendency that the above problem becomes significant and such a problem is pointed out likewise in the case of the pouch spout described in Patent Document 2.

Also, the package bag with a mouth portion of Patent Document 3 is reduced in the fear of the above problem because the dome-like projection disposed on the backside of the cap is in direct contact with the inner peripheral side of the opening.

However, in the structure disclosed in Patent Document 3, it is necessary to bind the outside periphery of the seal material with the outer plane of the opening end by fusion to prevent the seal material from peeling off when the dome-like projection is pressed against the seal material. There is therefore the problem that even if a tab portion for peeling is left, it is difficult to peel the seal material completely from the mouth portion when the seal material is opened and peeled. Moreover, because the seal material is in close contact with the dome-like projection, there is the problem that there is no place for escape of the pressure when the pressure in the container is raised in high-temperature sterilization or when an impact of falling is applied and a rise in inner pressure cannot be absorbed.

The present invention has been made in view of the above situation, and it is an object of the present invention to provide a sealing structure of a container which makes it easy to peel (opened peeling) a seal material when the container is opened while ensuring high sealing property by sealing the mouth portion of the container with the seal material and by providing the container with a lid, the structure enabling the container to prevent the seal material from peeling even if a impact of falling is applied or the pressure in the container is raised, and also to provide a lid used in this structure.

Means for Solving the Problem

A sealing structure of a container according to the present invention includes heat-sealing a seal member to the upper end of the mouth portion of a container and fitting a lid to said mouth portion to thereby seal the inside of the container, wherein an inner peripheral projection that is positioned in the vicinity of a place inner than the inner periphery of said mouth portion and is in direct contact with said seal member is formed on the top panel of said lid.

Such a structure ensures high sealing property and also, makes it easy to open and peel the seal member. Further, it prevents the peeling of the sealing material on the inner periphery of the mouth portion of which peeling is caused by an impact of falling or a rise in the pressure in the container, with the result that a phenomenon that the content of the container enters into the space between the upper end surface of the mouth portion and the seal member can be effectively avoided.

The sealing structure of a container according to the present invention may take a structure in which said lid is provided with a cyclic projection that is in contact with the upper end surface of said mouth portion through said seal member on the inside surface of the top panel thereof.

Such a structure can prevent the seal member from being peeled caused by a rise in the pressure in the container more reliably and also can prevent sterilizing water used in high-temperature sterilization from penetrating between the lid and the seal member.

The sealing structure of a container according to the present invention may take a structure in which said lid is fitted to said mouth portion so as to form a clearance between said lid and said seal member.

Such a structure allows the seal member to be curved upward in the lid to absorb an increase in pressure when the internal pressure in the container is increased.

Also, the sealing structure of a container according to the present invention may be one in which said lid is fitted to said mouth portion in a resealable manner.

Such a structure makes it possible to reseal the container with the lid also after the container is opened.

Also, the lid according to the present invention is one which is used in the aforementioned sealing structure of a container and fitted to the mouth portion of the container sealed with the seal material, is provided with a top panel covering said mouth portion and is provided with an inner peripheral projection that is positioned in the vicinity of a place inner than the inner periphery of said mouth portion and is in direct contact with said seal member on the inside surface of the top panel when it is fitted to the mouth portion. Also, the lid according to the present invention may have a structure provided with a cyclic projection that is in contact with the upper end surface of said mouth portion through said seal member on the inside surface of said top panel.

Effect of the Invention

According to the present invention, the mouth portion of a container is sealed with a seal member and a lid is fitted, thereby ensuring high sealing property and also making easy to open and peel the seal member, and further, it prevents the peeling of the sealing material on the inner periphery of the mouth portion by the inner peripheral projection formed on the inside surface of the top panel of the lid, with the result that a phenomenon that the content of the container enters into the space between the upper end surface of the mouth portion and the seal member can be effectively avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially broken sectional view showing the outline of an embodiment in which the sealing structure of a container according to the present invention is applied to a pouch spout.

FIG. 2 is an enlarged sectional view of an essential part of an embodiment shown in FIG. 1.

FIG. 3 is a plan view showing the condition that a seal member is heat-sealed to the upper end surface of an opening of a pouring cylinder.

FIG. 4 is a front view showing one example of a pouch with a spout.

DESCRIPTION OF THE REFERENCE NUMERALS

-   1 Spout -   10 Spout body -   12 Pouring cylinder (mouth portion of a container) -   13 Seal member -   15 Cap (lid) -   15 a Top panel -   15 d Cyclic projection -   15 e Inner peripheral projection -   2 Clearance

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments according to the present invention will be explained with reference to the drawings.

Here, FIG. 1 is a partially broken sectional view of a spout showing an embodiment in which the sealing structure of a container according to the present invention is applied to the pouch spout. FIG. 2 is an enlarged sectional view of an essential part enclosed by the chain line in FIG. 1.

A spout 1 shown in FIG. 1 has a spout body 10 provided with a boat-form portion 11 and an pouring cylinder 12 having a cylindrical form and extended upwards from the boat-form cylinder 12 and the upper end of an opening of the pouring cylinder 12 is heat-sealed with a seal member 13. Also, screw threads 14 for screw-fitting a cap 15 is formed on outside peripheral surface of the pouring cylinder 12 and provided with plural drain slits 14 a in a peripheral direction.

Then, as shown in drawings, the opening of the pouring cylinder 12 is sealed with the seal member 13 and the cap 15 is screw-fitted to the pouring cylinder 12 so as to cover the seal member 13. If the cap 15 is fitted to the pouring cylinder 12 by screw fitting in the above manner, this is preferable because the spout can be resealed by the cap 15 after opening. However, the fitting means of the cap 15 is not limited to the above means.

Also, in the example illustrated, the boat-form portion 11 contained in the spout body 10 is provided with a cylinder portion 11 a connected to the pouring cylinder 12, three welded substrate 11 b that project horizontally in a triangle form from this cylinder portion 11 a so as to be almost symmetrical in the figure and a flange portion 11 c positioned at the boundary between the pouring cylinder 12 and the cylinder portion 11 a.

This welded substrates 11 b are arranged at predetermined intervals along the direction of the center axis of the cylinder portion 11 a and are connected in a vertical direction through a column portion 11 d positioned at front end side. Also, a spout seal portion 35 of a pouch body 3 is heat-sealed with the entire periphery of the side surface of the welded substrate 11 b as described later. At this time, the flange portion 11 c is so devised that it is in direct contact with the side of the spout seal portion 35 and is aligned with a soft wrapping material forming the pouch body 3 (see FIG. 4).

In this embodiment, the spout body 10 and the cap 15 may be produced using a thermoplastic resin typified by a polyolefin resin such as polypropylene and polyethylene by a molding means such as injection molding.

Here, in this embodiment the spout 1 is given as the example. However, the present invention may be applied to various containers such as bottle type containers other than this spout 1.

When the present invention is applied to a bottle type container, the mouth portion of a bottle type container corresponding to the spout body 10 used in the above embodiment can be integrated with the container body by molding and besides the above polyolefin resins, various thermoplastic resins including polyethylene terephthalate and polyethylene naphthalate may be used. Though the bottle type containers may be produced by direct blow molding or stretch blow molding, the mouth portion of the container may be allowed to take a desired shape when a preform is molded by injection molding prior to the blow molding in the case of stretch blow molding.

In any of these embodiments, the cap and the mouth portion of the container may be produced using the same resins or by blending other thermoplastic resins or properly produced in known structures, for example, a multilayer structure using functional resins such as an oxygen barrier resin.

Also, the seal member 13 heat-sealed to the upper end surface of the opening of the pouring cylinder 12 is, as shown in FIG. 3, made of an almost circular film material and two projections 13 a are formed and projected in radius directions opposite to each other. These projections 13 a are formed as thumb arms making easy to peel the seal member 13 when the seal member 13 is opened and peeled. These projections are preferably formed in such a manner that when the cap 15 is fitted to the pouring cylinder 12, the projections 13 a are bent along the inside surface shape of the cap 15 whereas when the cap 15 is taken off from the pouring cylinder 12, they recover its shape by their elasticity.

It is to be noted that FIG. 3 is a plan view showing the condition that the upper end surface of the opening of the pouring cylinder 12 is heat-sealed with the seal member 13.

Examples of the film material used for the seal member 13 may include film materials having a multilayer structure in which a base material layer, an intermediate layer (barrier layer) and a sealant layer are laminated in this order through an adhesive layer. The specific structure of the film material may be properly selected in consideration of the required tensile strength, resistance to an impact of falling, pinhole resistance, resistance to the content, gas barrier property and also, heat resistance when high temperature sterilization such as hot water sterilization and retort sterilization is required.

In the case of using the film material of the above multilayer structure as the film material for the seal member 13, base material films superior in mechanical property such as tensile strength, resistance to the impact and pinhole resistance are preferably used for the base layer. Specifically, materials obtained by laminating biaxial oriented films made of, for example, polyester type resins such as polyethylene terephthalate, polyamide type resins such as nylon or polyolefin type resins such as polypropylene singly or plurally.

Such a base material film itself may be provided with barrier property according to the need by vapor-depositing, for example, a metal such as aluminum or an inorganic oxide such as alumina (aluminum oxide) and silica (silicon oxide), by coating this base material film with a barrier organic material such as polyvinylidene chloride and polyacrylic acid, or by blending an oxygen absorbing resin containing an oxidizing polymer or an oxygen absorber made of, for example, a reducing metal compound.

Also, as the intermediate layer, synthetic resin films provided with barrier property that stands to various gases and steam may be used.

Examples of such a synthetic resin film include an ethylene/vinyl alcohol copolymer film; vinylidene chloride copolymer film; crystalline polyamide film (Nylon MXD6) obtained by a polymerization condensation reaction between methaxylenediamine (MXDA) and adipic acid; acrylonitrile copolymer film; polyglycolic acid and its copolymer film; polyglycolic acid film; clay type nanocomposite synthetic resin film; inorganic film deposited film; films coated with a barrier organic material such as polyvinylidene chloride and polyacrylic acid; and films coated with, as a base, a clay type nanocomposite material such as a phenol resin, epoxy resin and polyimide resin. These films may be blended with an oxygen absorbing resin containing an oxidizing polymer and an oxygen absorber made of, for example, a reducing metal compound. Also, when no transparency is required, a metal foil (including an alloy film) such as aluminum foil or steal foil may be used as other materials imparting barrier property.

Also, it is demanded of the sealant layer to have heat-sealing property (which means that a subject material can be melted, diffused and resolidified at temperatures lower than the melting point of the material constituting at least the base material layer), heat-sealing strength, heat resistance (heat-sealing strength at high temperatures), resistance to contents and sanitary property.

Examples of the synthetic resin material having heat-sealing property adaptable to the sealant layer include polyolefin type resins such as low-density polyethylene, linear low-density polyethylene (Ziegler type (multisite catalyst) and metallocene type (single-site catalyst)), ethylene/α-olefin copolymer, olefin copolymer graft-modified by ethylene type unsaturated carboxylic acid or its anhydride, middle-density polyethylene, high-density polyethylene, polypropylene, propylene/ethylene copolymer, polybutene-1, polymethylpentene, ethylene/vinyl acetate vinyl copolymer, ethylene/acrylic acid copolymer, ethylene/methacrylic acid copolymer, ion-crosslinked olefin copolymer (ionomer) obtained by introducing a metal ion into a part of a ethylene/methacrylic acid copolymer or the like and ethylene/tetracyclododecene copolymer (cyclic olefin copolymer); aromatic vinyl copolymers such as polystyrene and styrene/butadiene copolymer; vinyl halide resin such as polyvinyl chloride and polyvinylidene chloride; acrylonitrile copolymer such as an acrylonitrile/styrene copolymer and acrylonitrile/butadiene/styrene copolymer; polylactic acid type resin (including polymesolactide compound type); and polyester type resins having a relatively low melting point such as polybutylene terephthalate when the spout 1 is constituted of a polyolefin type resin. These resins may be used either singly or in combinations of two or more according to the need.

When the spout 1 is constituted of a polyester type resin, copolymer polyesters obtained by modifying polyethylene terephthalate or polybutylene terephthalate with a polyvalent carboxylic acid component such as isophthalic acid and adipic acid or a polyhydric alcohol component such as 1,4-butanediol and 1,4-cyclohexanedimethanol are preferably used as the synthetic resin material used in the sealant layer. Easily peeling ability can be imparted to the sealant layer by blending an incompatible synthetic resin material such as polyethylene and polypropylene in such a copolymer polyester.

Also, examples of materials used to form an adhesive layer that binds the above layers among them include polyurethane type resins such as a polyether type polyurethane resin and polyester type polyurethane resin, polyester type resins, epoxy type resins, acryl type resins and olefin type resins into which a polar group is introduced.

When a film material having such a multilayer structure is used as the seal member 13, synthetic films constituting each layer may be obtained by a usual method such as a casting method, T-die method, calendering method or inflation method. Then, the film material having a multilayer structure may be obtained by a usual method such as dry lamination method using a film molded in advance and a sandwich lamination method, lamination coating method or melt co-extrusion method using a molten resin. At this time, in order to improve the adhesiveness of each of the base material layer, intermediate layer and sealant layer, the surface of each layer, which surface is in contact with the adhesive layer may be subjected to surface reforming treatment using corona discharge treatment, flame treatment, ultraviolet treatment, ozone treatment, primer coating treatment (coated with alkyl titanate, polyethyleneimine, a silane coupling agent, isocyanate type compound or a polyurethane type compound).

Also, in the example illustrated, the cap 15 is provided with a top panel 15 a that covers the opening of the pouring cylinder 12 and a thread groove 15 b corresponding to a screw thread 14 of the pouring cylinder 12 is formed on the inside peripheral surface of a cylinder wall 15 c descending from the peripheral end of the top panel 15 a. Moreover, a cyclic projection 15 d that is in contact with the upper end surface of the opening of the pouring cylinder 12 through the seal member 13 is formed on the inside surface of the top panel 15 a. The cyclic projection 15 d is formed along the upper end surface of the opening of the pouring cylinder 12, such that the seal member 13 is pressed against the upper end surface of the opening of the pouring cylinder 12 by the cyclic projection 15 d.

Such a structure ensures that even if the seal member 13 is raised upward along with a rise in the internal pressure, for example, in high-temperature sterilization or when an impact of falling is applied, it is possible to efficiently prevent the occurrence of a phenomenon that the seal member 13 is peeled from the upper end surface of the opening of the pouring cylinder 12 and the sealing property of the container (pouch) can be retained.

Therefore, in this embodiment in which the seal member 13 is prevented from peeling by the cap 15 fitted to the pouring cylinder 12, the seal strength of the seal member 13 is determined without the necessity for considering high-temperature sterilization after the content is filled and sealed and peeling during the distribution process and may be properly set, for example, to a range from 5 to 25 N/15 mm and particularly 15 N/15 mm or less by giving priority to easy peeling ability.

In the case of carrying out retort sterilization as the high-temperature sterilization, the seal strength is fixed to 23 N/15 mm or more according to the related law. However seal strength for the seal member 13 can be selected in the above range.

Moreover, if sterilizing water used in the high-temperature sterilization penetrates between the cap 15 and the seal member 13 and is left unremoved in the product, and the product is put in a distribution process, there is a fear that the product is misunderstood as a defective as if the content leaked. Because, in this embodiment, the cyclic projection 15 d is designed to be in contact with the upper end surface of the opening of the pouring cylinder 12 through the seal member 13 and it is therefore possible to prevent sterilizing water from penetrating into the upper surface of the seal member 13.

Also, in the example illustrated, a cyclic inner peripheral projection 15 e located on the inner peripheral side of the cyclic projection 15 d is formed concentrically together with the cyclic projection 15 d on the inside surface of the top panel 15 a of the cap 15. This inner peripheral projection 15 e is formed such that the tip side of the inner peripheral projection 15 e is in contact with the seal member 13 when the cap 15 is fitted to the pouring cylinder 12. Also, this inner peripheral projection 15 e is formed such that it has such a projected length allowing the tip thereof to be positioned below the horizontal plane including the upper end surface of the opening of the pouring cylinder 12 when the cap 15 is fitted to the pouring cylinder 12 (see FIG. 2).

Although in the example illustrated, the tip of the inner peripheral projection 15 e is designed to be positioned below the horizontal plane including the upper end surface of the opening of the pouring cylinder 12, it is only required that the tip of the inner peripheral projection 15 e is positioned on the horizontal plane including at least the upper end surface of the opening of the pouring cylinder 12 and is in contact with the seal member 13.

According to this embodiment, the inner peripheral projection 15 e like this is formed. Therefore, when force that likely lifts the seal member 13 upwards arises along with a rise in the internal pressure, the inner peripheral projection 15 e is pressed against the seal member 13 positioned in the vicinity of the inner periphery of the opening of the pouring cylinder 12 to thereby prevent the seal member 13 from peeling from the upper end surface of the opening at the inner periphery of the opening of the pouring cylinder 12.

Specifically, in this embodiment, the above cyclic projection 15 d and inner peripheral projection 15 e are formed for the following main purposes. Specifically, the above cyclic projection 15 d prevents the whole peeling of the seal member 13 from the upper end surface of the opening whereas the inner peripheral projection 15 e prevents the partial peeling of the seal member 13 at the inner periphery of the opening.

Here, if the position where the inner peripheral projection 15 e is formed far distant from the inner periphery of the opening, the inner peripheral projection 15 e cannot prevent the occurrence of the phenomenon that the seal member 13 positioned in the vicinity of the inner periphery of the opening of the pouring cylinder 12 is lifted upwards when the internal pressure is increased, with the result that the function of preventing the peeling of the seal member 13 at the inner periphery of the opening of the pouring cylinder 12 is damaged. For this, the inner peripheral projection 15 e must be formed between the inner periphery of the opening and a position distant about half the diameter of the opening of the pouring cylinder 12: specifically, at a position in the vicinity of a place inner than the inner periphery of the opening of the pouring cylinder 12 so as not to be too far from the inner periphery of the opening.

If even a part of the seal member 13 is peeled or a part which does not seal with the seal member 13 is present at the inner periphery of the opening of the pouring cylinder 12, the content in the container enters into that part and there is a fear of giving a feeling of discomfort to purchasers when the seal member 13 is opened and peeled. According to this embodiment, the inner peripheral projection 15 e that is in contact with the seal member 13 is formed on the inside surface of the top panel 15 a of the cap 15 to thereby prevent the seal member 13 positioned on the outer peripheral side than the inner peripheral projection 15 e from being lifted over the upper end surface of the opening of the pouring cylinder 12. This makes it possible to maintain the situation where the seal member 13 is in close contact with the upper end surface of the opening of the pouring cylinder 12 and it is therefore possible to effectively prevent the content of the container from entering between the upper end surface of the opening of the pouring cylinder 12 and the seal member 13.

In this embodiment, the inner peripheral projection 15 e is not limited to the above type having a cyclic form and may be one formed by arranging plural small projections cyclically insofar as the aforementioned function is obtained. Its specific structure may be modified properly to the extent that the aforementioned function is not damaged.

Also, the example illustrated is so designed that a predetermined clearance 2 is formed between the cap 15 and the seal member 13 when the cap 15 is fitted to the pouring cylinder 12. Such a structure allows the seal member 13 to be curved upward in the cap 15 to absorb an increase in pressure when the internal pressure in the container is increased in high-temperature sterilization or when an impact of falling is applied, so that an impact applied to the seal member 13 when the internal pressure is increased is eased.

The spout 1 as mentioned above is fitted to a pouch body 3 as shown in FIG. 4 and used as a mouth that pours the content.

In the example illustrated, the pouch body 3 is constituted of a body portion 31 and a bottom portion 32 formed of a soft wrapping material such as a resin film. The side periphery of the body portions 31 is sealed with a side seal 33 in the condition that the bottom portion 32 is folded at a fold line 32 a and also, the body portion 31 and the bottom portion 32 are sealed with a bottom seal 34. Also, a slant portion 4 that is cut diagonally is formed at a corner portion on the upper left side in the figure. In a spout seal portion 35 of this slant portion 4, the entire periphery of the side surface of the welded substrate 11 b of the spout 1 is heat-sealed with the soft wrapping material forming the pouch body 3.

Such a pouch with a spout is generally conveyed to a content-filling step in the condition that its top portion is opened and the top portion is sealed with a top seal 36 after the content is filled. At this time, the spout 1 fitted as the pouring mouth has s structure in which the opening of the pouring cylinder 12 is sealed with the seal member 13 and the cap 15 is fitted to the pouring cylinder 12 so as to cover the seal member 13. For this, the seal strength of the seal member 13 is designed to be at such a level that the seal member 13 is easily peeled, the content can be filled and sealed highly tightly. When the content is poured, the seal member 13 is opened and peeled after the cap 15 is dismounted. At this time, the seal member 13 can be heat-sealed at such a strength level that it is easily peelable. The seal member 13 can be therefore peeled and opened easily.

Although the invention has been described in its preferred embodiment, the present invention is not limited to the above embodiment. It is needless to say that various modifications and variations are possible within the scope of the present invention.

For example, in the aforementioned embodiment, the inner peripheral projection 15 e is formed, together with the cyclic projection 15 d that is in contact with the upper end surface of the opening of the pouring cylinder 12 through the seal member 13, on the side inner than the cyclic projection 15 d on the inside surface of the top panel 15 a of the cap 15. However, if the seal member 13 is prevented from peeling from the upper end surface of the opening only by the inner peripheral projection 15 e and sufficient sealing property can be secured, the above cyclic projection 15 d may be omitted according to the need.

Also, the example in which the present invention is applied to a pouch spout is given in the above embodiment. However, the container to which the present invention may be applied is not limited to a pouch as those mentioned above. The present invention may be applied to, for example, a squeeze bottle to be filled with a content such as mayonnaise or a wide-mouth container to be filled with a content such as jam. However, the present invention is preferably used for containers, such as a pouch and squeeze bottle, made of flexible materials which are largely deformed and allow a large increase in internal pressure when an impact of falling is applied and a person in charge grasps these containers strongly during the distribution process.

INDUSTRIALLY APPLICABILITY

As explained above, the present invention provides a sealing structure of a container which makes it easy to open and peel a seal member while securing high sealing property by sealing the mouth portion of the container with the seal member and by providing the container with a lid, whereby the present invention may be utilized in various containers. 

1. A sealing structure of a container, the sealing structure comprising heat-sealing a seal member to the upper end surface of the mouth portion of a container and fitting a lid to said mouth portion to thereby seal the inside of the container, wherein an inner peripheral projection that is positioned in the vicinity of a place inner than the inner periphery of said mouth portion and is in direct contact with said seal member is formed on the inside surface of the top panel of said lid.
 2. A sealing structure of a container according to claim 1, wherein said lid is provided with a cyclic projection that is in contact with the upper end surface of said mouth portion through said seal member on the inside surface of the top panel thereof.
 3. A sealing structure of a container according to claims 1, wherein said lid is fitted to said mouth portion so as to form a clearance between said lid and said seal member.
 4. A sealing structure of a container according to claim 1, wherein said lid is fitted to said mouth portion in a resealable manner.
 5. A lid fitted to the mouth portion of a container sealed with a seal member, the lid comprising: a top panel covering said mouth portion; and an inner peripheral projection that is positioned in the vicinity of a place inner than the inner periphery of said mouth portion and is in direct contact with said seal member on the inside surface of the top panel when it is fitted to the mouth portion.
 6. A lid according to claim 5, the lid having a cyclic projection that is in contact with the upper end surface of said mouth portion through said seal member on the inside surface of said top panel. 